Electronic tube



1943- o. T. MCILVAINE 2,307,697

ELECTRONIC TUBE Original Filed July 9, 1954 i lwi s- Patented Jan. 5,1943 2,307,697 4 ELECTRONIC TUBE Oran T. McIlvaine, St. Charles, Ill.

Original application July 9, 1934, Serial No.

734,352. Divided and this application Decemher 5, 1940, SerialNo.368,711

5 Claims. (01. 250-165 This application is a division of my applicationon Electronic device, filed .July 9, 1934, Serial No. 734,352 which wasa continuation-inpart of my application, Ser. No. 209,281, filed July29, 1927, forElectronic tubes, which appli-.

ction matured into Patent No. 1,965,849, on July 10, 1934.

This invention relates to electronic devices, such as, electronic tubesfor use in connection with the transmission and reception ofelectromagnetic impulses or radio signals.

Attempts have been made heretofore to, combine a photo-electric tubewitha thermionic tube, with the photo-cathode connected with the grid of thethermionic tube in one envelope, but the action was the same as when twoseparate envelopes were employed, resulting only in a more complex andexpensive structure.

The primary object of this invention is to combine a photo-electric tubewith a thermionic tube so that the electronic streams are intermingledin controlling the thermionic emission directly by the fiow ofphoto-emission from the photocathode, the two currents being reactive inthe space between the various elements of the tube,

the electronic streams themselves being employed for controlling theaction.

The present invention has for further objects thereof the provision ofan electronic tube of simple and inexpensive construction which willoperate successfully for an indefinitely long period of time; theprovision of a simple and inexpensive type of tube which can be usedwith either direct or alternating current or other sources of lightandheat; the provision of a power tube with a light-sensitive electrodefor controlling,

by the fiow of photo-emission therefrom, the elec-' tron emission of thethermionic cathode of the tube by changing the potential of either theanode or grid of the tube; and the provision of 'a H light-sensitivepower tube, having associated therewith, a light source which may bemodu- Fig. 3 is a vertical sectional view of another or modified form oftube; and

Fig. 4 is a'transverse sectional view thereof.

In the form of the invention shown in Fig. 1,

the tube comprises a sealed glass container in the form of an envelopehaving a side wall I fused at its lower. end 2 to a tubular stem orpress 3v which carries the various elementsof the tube.

The tube maybe highly evacuated or' it may be filled with one of theinert gases such as, neon. A The elements of the tube shown in Fig. 1,include o a hot cathode in the form of a wire filament 4, alight-sensitized grid element 5, .ananode element 8, an anode i and asupport 8 for the foregoing elements. l

The anode 1 can also be used to collect the. electrons emitted from thehot cathode 4, it being. controlled in accordance with the variation inlight impinging on the sensitized grid element'5 supplied from a 1ightsource (not shown) fluctuating in accordance with'incoming signalstransmitted by a fluctuating current. Both the anode element 6 and theanode 1 may be'used for the same purposeor either one of them may beoperated as a photo-anode and the -0ther-asa thermionic anode by theselection and use of proper electrical connections (not shown) as will Ibe understood byone familiar withthe' art to which this inventionrelates.

By properly choosing the circuit constants for V these two circuits,many novel results canbe obtained. In this particular device, the griditself is photo-sensitized and it-varies the hot cathode emission fromthe filament t to the anode element 6 or the anode 1. Lead wires H), II,l2and l3, traversing the press 3 of the tube, are connected to the anodeelement 6,-each of the terminals'of the hot cathode 4, the grid element5 and the' anode 1 respectively. r

lated or controlled by or in accordance with incoming radio signals orelectric impulses.

With these and other objects in view, the invention consists in thenovel construction, arrangement and combination of parts, hereinafterillustrated and described in some of its embodiments in the accompanyingdrawing, and

particularly pointed out in the appended claims.

In the drawing, certain illustrated embodi- The sensitizing of the grid5 in Fig. 1, controlling the emission'of electrons under the influence Iof light acting thereon, renders far more elfective the electron streamfrom the hot cathode to the anode of the thermionic tube, than ifthephoto-emission were used merely to change the I potential on the grid.Each electron emitted by I the gridunderthe influence of light has amuch merely to change the potential on the grid. I

In Fig. 3 there is a modified form of tube in r which aphoto-cathode-Mlis locatedon the inner I surface of the outer wall 3| ofthe tube and-it consists of a material, manyof which are known, whichemits electrons when exposed to light. An I r anode 32 made ofa'net-work of wires which-a1- better control than if it were used lowsthe passage of light from a heated filament 33 is arranged to absorb andcarry away the electrons emitted by the filament 33. The flow ofelectrons from the cathode or filament 33 to the anode 32 may becontrolled by a grid element 34.

The potential of the grid 34 may be controlled by the electrons emittedfrom the photo-cathode 30 which in this case is on the inside of thetube, and these electrons are drawn to the grid 34, which in thisrespect is the anode for the photo-cathode 38. This current flow, bychanging the potential on the grid 34, thereby controls the electronstream from the hot cathode 33 to the anode 32.

In this form, the grid 32 forms the anode for the photo-cathode 30,while the grid .34 zconsti tutes the anode for the hot cathode 33. Thusthe efiect of a much greater gridlcontrol once, thermionic electron flowthan if :the voltage of number of tubes formerly thought necessary toproduce the desired degree of amplification of radio or wireless signalswithout objectionable distortion.

The tubes may be either highly evacuated or they may be filled with oneor more inert gases commonly used for such purpose.

While the light sources described in connection with the tubes shown inFigs. 1 and 3, are not specifically illustrated in the drawing, it isintended that any suitable source of radiant energy, ivisible'iorinvisible, which fluctuates under the influence ofa fluctuatingelectrical current, might be used in connection with the various tubesPhoto-icathodes can be selectively sensitized to =iespohdto'-'difierentfrequencies of light by utiliz- -"ing the selective photo-electricefiect which is a grid 32 were varied from. an outside potential. Inthis Way the electron streams themselves are poses,.such'as where acertain bias voltage is not required on. the grid34, a black emitter canbe used which gives no light and has no substantial effect on :thephoto-cathode. A cathode of this type would be a caesiatedtungstencathode or some similar cathode as describedin the tubes ofapplication, Serial No. 209,281, previously referred to, now Patent No.1,9 65,849.

Another: manner of using the tube shown in Fig. 3 Lwouldzbe that ofusing. the wire network 32 as the'grid and using the coil 34 as theanode, in which. case electrons-are supplied to the anode 34 by-thefilament 33 which is preferably heated to incandescence for suchpurposeand also for the purpose. of providing-a light source for the excitationof the photo-cathode 30. With this arrangement, the fixed bias on thegrid 32 may be varied through the control of the electron emission ofthe photo-cathode 36 by changing the brilliancy of. the filament 33.light incident upon the photo-cathode would then operate around thispoint as an operation point.

Light may be admittedto the surface of the photo-cathode through thephoto-cathode itself which consists of alight-sensitized transparentfilm of metalon the inside wall otthe tube, or

e if an opaque coating is used, light can be admitted through either endof the tube by omitting the coating at these p0ints, 0r as is done inthe present-case, light can be admitted, through one Any fluctuatingside of the tube by omitting the coating there as is done in the tubeshown in Fig. 3. Suitable leads 35, 36, 31 and 38 traverse a press 39sealed in the tube and they are connected respectively l electrons, asfor example,the hot and cold cath' odes shown, the latter of which iscontrolled by a source of light,-so that the operation of the tub.

can be-varied and controlled by means of a light sourcehavingnoelectrical connection with the 7 tube elements.- a The use of a lightsource in this manner is of tremendous advantage in some typesof radiowork and by the proposed use of the tubes shown herein, it is possibleto greatly reduce the 73 characteristic of the alkali and alkaline earthmetals'and also by having the light strike the photo-cathode withanangleoi incidence-oi about 60, in -wliich case, the different .metalsshow a strong maximum of photo-electric sensibility over a very shortpart or the-spectrum, which-dire i fers withthe dinerent metals: andwmch maxi-t mum enect may be varied through selectionof thepropermetals'so:astooccur. at different predeterminedportion's oi' thespectrum. a i

By Iorming the cathode suliaceirom.such

metals as, caesium;--rubldium, potassium' and sotions OI thevlsmiespecti um'. I :l'his pnase'oi: the

invention-mightbe utilized in color television- =1 Work and thetransmission: or" images their natural colors.

One or the more important features of I this invention is that oremploying a relatively small"- PAOLO-CUITBHVOIE '-primary emlssion -tocontrol i a a relatively large --tnermloniccurrent directly inproportion to th'e photo-current; thereby giving a 1 nigh amplincation'oi' anorigmarreebleimpulse, and many mOCUIICaBiOIISOf thegenerai"principles- 1 or tube construction--disclosedherein; may be particular-I'orms of electronic eevices shown and described, and the-particularprocedure-set :iorth, are presented -Ior purposes -oiexplanation, and I!H that variousmodifications ofsaid apparatus-and procedure can' be madewithoutoeparture from this invention as" described -in' the appendedclaims;

. I claim:

1. An electronic-tube comprisingan envelop'e having assembled therein anelectronic cathode' and an anode spaced'thereirom,'a photo-cathode and apnoto anode' therefor mounted in spaced--- 4 relation" insaid'envelope;one oi' said photo elementsbeing intermediate the first-"mentionedelectronic elements, and one ofsaid-electronic elements being in theelectron'path formed-bythe photo elements,

2. An electronic'tubacomprising anenvelope a having'assembled therein anelectronic cathode and an anode spaced therefronr, a photo-cathode and aphoto-ano'de'therefor mounted in-spaced" relation in said e'nvelope,'oneof said photo elements being intermediate the first-mentioned electronicelements, and one of said electronic elements being in the electronicpath from the photo-cathode to the photo-anode forming intersectingelectron paths,

3. An electronic tube comprising an envelope having assembled therein anelectronic cathode and an anode spaced therefrom, a photo-cathode and aphoto-anode therefor mounted in spaced relation in said envelope, one ofsaid photo elements being intermediate the first-mentioned electronicelements, and the first-mentioned anode being in the electron path ofthe photo elements.

4. An electronic tube comprising an envelope having assembled in achamber therein an electronic cathode and anode spaced therefrom and acontrol element, a photo-cathode and a photoanode therefor mounted inspaced relation in said chamber of the envelope, one of said photoelements being formed on the control element.

5. An electronic tube comprising an envelope having assembled in achamber therein an electronic cathode and anode spaced therefrom and acontrol element, a photo-cathode and a photoanode therefor mounted inspaced relationin said chamber of the envelope, one of said photoelements being formed on the control element intermediate thefirst-mentioned electronic elements, and one of the first-mentionedelectronic elements being in the electron path of the photo 15 elementsforming intersecting electron paths.

ORAN T. MCILVAINE.

